Controlling the transfer of a wafer within a plasma cluster tool environment can be a complex and tedious process. As discussed herein, a plasma cluster tool relates to an integrated multi-module plasma processing system. Generally, a wafer undergoes a series of process steps in various wafer-holding locations by the time the wafer completes an etching cycle.
As discussed herein, a wafer-holding location relates to a given node within a given module. Examples of modules include, but are not limited to, process modules, airlock modules, vacuum transfer modules, atmospheric transfer modules, and ports. Each module may have a plurality of nodes (i.e., slots), from one to an nth number of nodes. For example, a process module usually has one node while an airlock module generally has two nodes. Thus, an example of a wafer-holding location is node 1 of airlock module 1.
The transfer of a wafer between wafer-holding locations is usually handled by a centralized handling module. A user at the centralized handling module creates wafer transfer instructions (i.e., macro commands or sequences) that may involve a combination of menus, buttons and icons to enable wafer movement. Further, to move a wafer from an origination wafer-holding location (i.e., source module with source node) to a destination wafer-holding location may involve multiple intermediate wafer transfer instructions. Thus, a successful wafer movement may be dependent upon skills and reliability of the user. However, even if the user is skilled in the creation of wafer transfer instructions, the sheer number of parameters that the user may have to provide to complete a wafer movement increases the likelihood that an error may occur.
To facilitate discussion and to illustrate the possible complexity of creating and executing wafer transfer instructions, FIG. 1 shows a menu-driven interface, which is coupled with a graphical animated overview of the current state of a plasma cluster tool. Section 100 shows an animated graphical overview of the current state of plasma cluster tool 101. Section 119 shows a menu driven interface that user employs to create wafer transfer instructions to move wafers within plasma cluster tool 101. Plasma cluster tool 101 generally consists of various wafer-holding locations that enable a wafer to be processed as it moves from a port through an atmospheric transfer module (ATM) to a vacuum transfer module (VTM) to one or more process modules and ultimately back out to a port.
A wafer is placed in one of the ports (110, 112, 114). An ATM 125, which may be a robotic arm, moves the wafer to an aligner 107. Aligner 107 allows the wafer to be centered properly before the wafer is etched. Once centered, the wafer is moved by ATM 125 to one of the airlock modules (121 and 123). Since airlock modules have the ability to match the environment between an atmospheric transfer module and a vacuum transfer module, the wafer is able to move between the two pressure environments without being damaged.
From an airlock module, the wafer is moved into one of the process modules (102, 103, 104 and 105) by one of the robotic effectors (109 and 111) in vacuum transfer module (VTM) 108. To move between process modules, one of the robotic effectors in VTM 108 is used. For example, to move from process module (PM) 102 to PM 104, the wafer is moved from PM 102 to VTM 108. From VTM 108, the wafer is moved to PM 104.
Once the wafer has been processed, the wafer is moved from the process modules (102 and 104) to one of the airlock modules (121 and 123) by one of the robotic effectors (109 and 111) in VTM 108. At the airlock module (i.e., 123), the wafer may be moved via ATM 125 to one of the ports (110, 112, 114) or to aligner 107.
With the aid of the graphical animated overview in section 100, a user is able to employs section 119 to create wafer transfer instructions. Section 119 is divided into 2 main sections: VTM commands 171 and ATM commands 173. Assuming that a wafer is in PM 102, the user wants to move the wafer to port 110. To create wafer transfer instructions to execute the wafer movement for the example mentioned above, the user has to create two different sets of wafer transfer instructions. The set of first wafer transfer instructions, which are defined in VTM commands 171, move the wafer from PM 102 to one of the airlock modules. The second set of wafer transfer instructions, which are defined in ATM commands 173, move the wafer from one of the airlock modules to port 110.
To create the set of first wafer transfer instructions, the user identifies an origination wafer-holding location, an intermediate destination wafer-holding location, and a robotic effector that will move the wafer from the origination wafer-holding location to the intermediate destination wafer-holding location. First, at fields 120 and 122 the user has to identify a module and node respectively for the origination wafer-holding location (i.e., node 1 of PM 102).
Then the user has to define the intermediate destination wafer-holding location. The intermediate destination wafer-holding location may be another PM (PM 104, PM 103, or PM 105) or it may be one of the airlock modules (121 or 123). For example, the parameters for fields 124 and 126 may be node 1 of airlock module 123. Finally, to complete VTM commands 171, the user has to identify at field 136 which robotic effector (i.e., 109) in VTM 108 to use.
To move the wafer to its final destination wafer-holding location at port 110, the user identifies an intermediate origination wafer-holding location and a destination wafer-holding location at ATM commands 173. First, at fields 152 and 154, the user identifies the module and node respectively for the intermediate origination wafer-holding location (i.e., node 1 of airlock module 123). The intermediate origination wafer-holding location defined in ATM commands 173 may the same intermediate destination wafer-holding location identified in VTM commands 171. Then the user identifies the destination wafer-holding location parameters for fields 156 and 158 (i.e., node 1 of port 110). To execute the command, the user pushes button 174.
The example above describes a transfer of a wafer from a module to a port. However, wafer movement is bi-directional. For example, a wafer at port 110 needs to be moved to PM 102 to be processed. In this situation, a user has to first create wafer transfer instructions in ATM commands 173 to move the wafer from the port through the ATM. Then the user creates wafer transfer instructions in VTM commands 171 to move the wafer to the designated process module.
In another example, a user may only want to move a wafer to an intermediate wafer-holding location. For example, the user wants to move the wafer at PM 102 to VTM 108. To accomplish this transfer, the user may use a “Pick” option, which requires the user to identify an origination wafer-holding location in fields 132 and 134 (module and node respectively) and to determine a robot effector in field 136.
Likewise, if the user wants to move the wafer from VTM 108 to PM 102, then the user may use a “Place” option, which requires the user to identify a destination wafer-holding location in fields 128 and 130 (module and node respectively) and to determine a robot effector in field 136. A similar “Pick” (fields 172 and 168) and “Place” (fields 170 and 166) options exist in ATM commands 173.
FIG. 2A and FIG. 2B both provide flowcharts of the steps a user may take in order to move a wafer to a desired wafer-holding location. FIGS. 2A and 2B are described in reference to FIG. 1 with the assumption that a user wants to move a wafer from PM 102 to port 110. FIG. 2A describes the steps a user takes in VTM commands 171 and FIG. 2B describes the steps a user takes in ATM commands 173.
At step 204, the user selects VTM commands 171. At step 206, the user selects a source module (i.e., enter PM 102 as the parameter for field 120). Then at step 208, the user selects a source node (i.e., enter 1 in field 122). At step 210, the user selects an intermediate destination module (i.e., enter airlock module 123 in field 124). Step 212 requires the user to select an intermediate destination node (i.e., enter 2 in field 126). At step 214, the user selects a robot effector (i.e., choose robotic arm A in field 136). At step 216, the user executes and waits for the wafer transfer instructions to be completed. At step 218, if the wafer is not at an intermediate destination wafer-holding location, then the process may start again at step 206 if the user wants to create another wafer transfer instructions.
However, if at step 218, the wafer is at an intermediate destination module, then the user proceeds to step 250. At step 250, the user selects ATM commands 173. At step 252, the user selects an intermediate source module (i.e., enter airlock module 123 in field 152). Then the user selects an intermediate source node (i.e., enter 2 in field 154). Parameters for steps 252 and 254 may be the same as those in steps 210 and 212 respectively. At step 256, the user selects a destination module (i.e., enter port 110 in field 156). Then, at step 258, the user selects a destination node (i.e., enter 1 in field 158). At step 260, the user executes by pushing button 174.
At step 260, if the wafer movement is complete (step 262), then the user proceeds to step 264 and the whole process is done. However, if the wafer movement is not complete, then the user returns to step 250 and proceeds to go through the steps again until the wafer is at its final destination wafer-holding location.
As described above, to move a wafer from a module to a port involves multiple wafer transfer instructions, which require a user to make multiple inputs. The user is not just required to define an origination wafer-holding location and a destination wafer-holding location, but the user may also have to select the mechanism by which the transfer is to be accomplished. As a result, the user needs to be knowledgeable in order to assure that the creation of wafer transfer instructions ensures a successful wafer movement.
There are several problems with the current methods for wafer movements. One, to create wafer transfer instructions requires a user to enter specific parameters. Thus, the user not only needs to know an origination wafer-holding location and a destination wafer-holding location, but the user may also have to define the transfer mechanism and an intermediate destination wafer-holding location. Since the user has to enter various parameters to create wafer transfer instructions, the possibility of errors increases.
Second, the user is limited by a graphical overview that may provide the user with the current state of a plasma cluster tool. Assume that a wafer currently occupies one of the wafer-holding locations in the plasma cluster tool (i.e., user sees that airlock module 121 is occupied by a wafer). However, the graphical overview may only allow the user to see that a module is occupied and does not identify which node is occupied (i.e., user is unable to determine whether the wafer is in node 1 or node 2). To prevent the risk of the two wafers being broken when one wafer tries to move into an occupied node, a skilled user may have to eliminate the possibility of using the occupied airlock module (i.e., 121) as the next wafer-holding location and chose another airlock module instead. However, if the user chooses to place a wafer into the occupied node, then two wafers will be broken and the plasma cluster tool will have to be shut down in order to clean the broken pieces from the wafer-holding location.
A third problem that exists occurs when an emergency arises and a plurality of wafers has to be removed in a timely manner. For example, a power outage occurs and the user is informed that he has five minutes to remove all wafers from a plasma cluster tool. The user has the option of physically removing the wafers from the plasma cluster tool or to create wafer transfer instructions to remove each wafer from the plasma cluster tool. In either case, the user runs the risk of making a mistake and causing damages to the machine as he quickly tries to remove the wafers from the plasma cluster tool within a short time span.